Reforming with a group IIB-containing catalyst

ABSTRACT

A catalytic composition of matter comprising 0.01 to 5 weight percent of a platinum group component, 0.01 to 5 weight percent of a Group IIB component, 0.01 to 3 weight percent of a component selected from the group consisting of a rhenium component and a germanium component and 0.1 to 3 weight percent of a halogen in association with a porous solid carrier and processes for the hydroconversion of hydrocarbons using said catalyst.

CROSS-REFERENCE

This application is a continuation-in-part of copending Waldeen C. Buss'application Ser. No. 200,121, filed Nov. 18, 1971, now abandoned whichin turn is a continuation-in-part of Ser. No. 132,715, filed Apr. 9,1971. now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to hydrocarbon hydroconversionprocesses, and more particularly, to reforming processes. Still moreparticularly, the present invention is concerned with a catalyticcomposition and a process for the hydroconversion of hydrocarbons in thepresence of the catalytic composition. The catalyst comprises a platinumgroup component and a Group IIB component, preferably zinc or cadmium,in association with a porous solid carrier. The catalyst mayadvantageously also comprise 0.01 to 3 weight percent of a secondcatalyst component, preferably selected from the group consisting of arhenium component, a tin component, a germanium component, and a leadcomponent.

2. Prior Art

Hydrocarbon hydroconversion processes, such as hydrocracking,hydrogenation, hydrofining, isomerization, alkylation, desulfurizationand reforming, are of special importance in the petroleum industry as ameans for improving the quality and usefulness of hydrocarbons. Therequirement for a diversity of hydrocarbon products, including, forexample, high quality gasoline, has led to the development of manycatalysts and procedures for converting hydrocarbons in the presence ofhydrogen to useful products. A particularly important hydrocarbonhydroconversion process is reforming. Although many features of thepresent invention are discussed in terms of reforming, it is to beunderstood that the present invention relates to other hydrocarbonhydroconversion processes as well.

In the development of catalysts for catalytic hydroconversion processes,it is important that the catalyst exhibit not only the capability toinitially perform the specified functions but also that it has thecapability to perform satisfactorily for prolonged periods of time.Thus, in the development of new catalysts, attention must be directed tothe activity, selectivity, and stability characteristics of thecatalyst. The activity of a catalyst is a measure of the catalyst'sability to convert hydrocarbon reactants to products at a specifiedseverity level, i.e., at a particular temperature, pressure,hydrogen-to-hydrocarbon mole ratio, etc. The selectivity of the catalystrefers to the ability of the catalyst to produce high yields ofdesirable products, and accordingly low yields of undesirable products.The stability of a catalyst is a measure of the ability of the catalystto maintain the activity and selectivity characteristics over aspecified period of time. Thus, for example, a catalyst for successfulreforming must possess good selectivity, i.e., be able to produce highyields of high octane number gasoline products and accordingly lowyields of light hydrocarbon gases. The catalyst should also possess goodactivity in order that the temperature required to produce a certainquality product need not be too high. Also, the high stability isdesired so that the activity and selectivity characteristics can beretained during prolonged periods of reforming operation. Thus, thetemperature stability, which is generally referred to as the foulingrate of the catalyst, desirably is such that the temperature need not beraised at a high rate in order to maintain conversion of the feed to aconstant octane product. Also, the yield stability of the catalystdesirably is such that the amount of valuable C₅ + gasoline productsdoes not decrease appreciably during prolonged operation at a constantconversion.

As indicated above, the present invention is particularly concerned withcatalytic reforming, that is, the treatment of naphtha fractions orfeeds to improve the octane rating. Catalytic reforming operations arecharacterized by employing catalysts which selectively promote suchhydrocarbon reactions as dehydrogenation of naphthenes to aromatics,dehydrocyclization of paraffins to naphthenes and aromatics,isomerization of normal paraffins to isoparaffins, and hydrocracking ofrelatively long-chained paraffins. Most catalysts used in reformingprocesses comprise platinum group components, particularly platinum, inassociation with porous solid carriers, for example, alumina. Researchefforts have been expended to seek substitutes for platinum and/or toseek catalytic promoters to use with platinum catalysts to increasetheir activity, stability and selectivity characteristics.

For example, U.S. Pat. No. 3,415,737 is the recent basic patent directedto the use of platinum-rhenium catalysts for catalytic reforming,particularly reforming of low sulfur content naphtha feedstocks. Use ofthe platinum-rhenium catalyst (specifically platinum-rhenium-inorganicsupport-halide) of U.S. Pat. No. 3,415,737 has been found to result inimproved yield stability and fouling rate stability compared to thatachieved with platinum catalysts containing no rhenium.

That is, the decline in C₅ + liquid yield of a product of given highoctane is lower than with the non-rhenium catalyst as a function oftime, and also the increase in temperature in order to maintain a givenhigh octane for the C₅ + product as the on-stream time progresses islower than with the non-rhenium catalyst. The discovery of aplatinum-rhenium catalyst for reforming low sulfur naphthas was thusregarded as an advance of major significance by the petroleum industryand as the most important development in the catalytic reforming fieldin the last 20 years or so; i.e., since reforming with aplatinum-alumina catalyst was first introduced into the petroleumindustry in place of the previously used molybdenum-alumina typecatalysts; see "New Reforming Catalyst Features Improved Stability, HighYields" by D. H. Stormont, Oil and Gas Journal, Apr. 28, 1969, pages63-65.

In view of the long time between the platinum-alumina and the improvedplatinum-rhenium-alumina reforming process, and the difficulty that laidbetween the basic platinum-alumina catalyst and finding a significantlyimproved new catalyst, namely the platinum-rhenium-alumina catalyst andits particular manner of use, it would indeed be unexpected to findstill further improvements in catalytic reforming processes due to stillfurther improved catalysts. However, the subject of the presentinvention is a further improvement in catalytic reforming due to animproved catalyst.

Before referring particularly to the present invention, two morerelevant areas of prior art might be mentioned, namely use ofplatinum-germanium catalysts for catalytic reforming and art involvinguse of catalysts containing Group IIB components such as zinc.

U.S. Pat. No. 2,784,147 is directed to a reforming process using analumina chromium oxide catalyst containing either germanium oxide,indium oxide or gallium oxide.

U.S. Pat. No. 2,906,701 is directed to a process for the reforming ofhydrocarbons with catalysts comprising a support and a "solid solution"comprising germanium and a metal such as platinum. In U.S. Pat. No.2,906,701 it is stated in Col. 3 that the exact state of the germaniumis not known but that the germanium and platinum should be coreduced.

U.S. Pat. No. 3,578,584 is also directed to the use of reforming using acatalyst containing platinum and germanium, and according to Example 1in U.S. Pat. No. 3,578,584 the catalyst is produced by a procedureinvolving coreduction of the platinum and germanium.

In all of the latter mentioned patents concerning germanium, there is noGroup IIB metal such as zinc in the catalyst.

Referring now to some relevant art concerning zinc, U.S. Pat. No.2,728,713 discloses a reforming catalyst comprising platinum on a basewhich is approximately equal molar zinc oxide and alumina oxide, forexample, 30 to 50 weight percent zinc oxide. Thus, the zinc oxide is aportion of the base for the catalyst rather than being an added metal asin the case of platinum or other metals which might be added to thecatalyst in the range of a few percent, say up to 5 percent or so. Thezinc oxide-alumina oxide base is referred to as a zinc aluminate or as azinc alumina spinel base. The formula for zinc alumina spinel is ZnOAl₂O₃, so that the amount of zinc is about 35 percent by weight of thesupport. Thus, U.S. Pat. No. 2,728,713 is not directed to using smallamounts of zinc in the reforming catalyst.

In a series of patents assigned to Kellogg Co., such as U.S. Pat. No.2,743,215, there is described catalysts which are prepared by methodscomprising adding a Group IIB metal such as mercury to an aluminum sol,and ultimately volatilizing the Group IIB metal such as mercury out ofthe catalyst. Thus, the mercury is an agent in the catalyst preparationrather than a component of the final catalyst. The mercury is sometimesreferred to as a promoting agent, but it could more properly be referredto as a treating agent. Thus it is stated in the patent that it ispreferred that the promoting agent volatilize from the catalyst mass ator before calcination temperatures, and that in some instances thepromoting agent is not volatilized at such temperatures, consequentlythe calcination operation may be conducted under sub-stmosphericpressures in order to remove substantially all of the promoting agentfrom the catalyst mass.

Example 1 of U.S. Pat. No. 2,743,215 illustrates the preparation method:a solution containing aluminum and mercury is prepared, a solutioncontaining platinum is added, the mixture is then dried and thencalcined at 1000° F. The finished catalyst is free of Group IIBcomponent, that is, free of mercury in this instance.

Group IIB metals such as zinc have been disclosed for use indehydrogenation catalysts, in Netherlands applications Ser. Nos. 6908540and 7008386. Netherlands Ser. No. 6908540 discloses dehydrogenationcatalysts containing Group VIIIB, e.g., platinum; and/or Group VIIB,e.g., rhenium; and Group IIB, e.g., zinc; and preferably an alkalicomponent such as sodium. The actual examples in Netherlands Ser. No.6908540 are of (a) dehydrogenation catalysts containing platinum plusGroup IIB, and (b) dehydrogenation catalysts containing rhenium plusGroup IIB. Netherlands Ser. No. 7008386 discloses dehydrogenationcatalysts containing Group VIIIB, e.g., platinum, and Group IIB, e.g.,plus zinc and preferably an alkali component such as sodium.

SUMMARY OF THE INVENTION

In accordance with the present invention, an improved hydroconversionprocess is conducted in the presence of a catalyst comprising a platinumgroup component, a Group IIB component, and a halogen associated with aporous solid carrier. The platinum group component is present in anamount of from 0.01 to 5 weight percent based on the finished catalyst;preferably the platinum group component is selected from the groupconsisting of a platinum component and a platinum component plus aniridium component. Preferably the Group IIB component is present in anamount from 0.01 to 5 weight percent and the halogen in an amount from0.1 to 3 weight percent, based on the finished catalyst.

According to a particularly preferred embodiment of the presentinvention, the catalyst also contains 0.01 to 3 weight percent of asecond catalyst component, preferably selected from the group consistingof a rhenium component, a tin component, a germanium component and alead component. The hydrocarbon hydroconversion process is preferablythe catalytic reforming of naphtha or gasoline fractions to produce highoctane products, because I have discovered that the aforementionedcatalysts, especially the catalysts with said second component, giveunexpectedly good results in catalytic reforming.

Also, in accordance with the present invention, a novel catalyticcomposition of matter has been discovered comprising a porous solidcarrier, preferably a porous inorganic oxide carrier, having associatedtherewith from 0.01 to 5 weight percent of a platinum group component,0.01 to 5 weight percent of a Group IIB component, and 0.1 to 3 weightpercent of a halogen. According to a particularly preferred embodimentof the present invention the catalyst composition of matter alsocontains 0.01 to 3 weight percent of a second catalyst component,preferably selected from the group consisting of a rhenium component, atin component, a germanium component and a lead component. The catalyticcomposition is preferably in a reduced state as defined later in thespecification. The novel catalyst of the present invention is found tobe highly active and stable for the reforming of naphtha and gasolineboiling range hydrocarbons and, in fact, is superior to commercialreforming catalysts containing only a platinum group component.

I have also found that the zinc level in the catalyst is a surprisinglyimportant variable. For example, with increasing amounts of platinumfrom say about 0.3 weight percent up to 1.0 weight percent or more,catalyst performance (such as fouling stability) is improved byincreasing the platinum, whereas increasing the zinc above about 0.5weight percent has been found in my experiments to decrease the foulingstability. Thus, according to particularly preferred embodiments of myinvention, the catalyst used in the catalytic reforming process containsless than 0.5 weight percent Group IIB metal, more preferably less than0.3 weight percent. The Group IIB metal used in the catalyst ispreferably zinc. The aforesaid low levels for a Group IIB metal such aszinc are especially preferred when the catalyst used in the catalyticreforming process of the present invention contains rhenium orgermanium. In the case of a catalyst containing 0.3 weight platinum, 0.3weight percent rhenium, and 1.1 weight percent chlorine on an Al₂ O₃support, in an accelerated catalytic reforming test run, I foundrelative fouling rates as follows as a function of zinc content:

                         Fouling Rate                                             Zinc, Wt. %          °F/Hr.                                            ______________________________________                                        0                    2.1                                                      .03                  1.4                                                      .08                  1.6                                                      .08                  1.35                                                     .18                  1.8                                                      .28                  2.3                                                      ______________________________________                                    

In my initial work with an added Group IIB metal, specifically addedzinc, I had failures in the sense that the catalyst was no better(actually somewhat worse) than the catalyst having no added zinc.Specifically, when I added about 0.3 weight percent zinc to a PtReAl₂ O₃reforming catalyst I found no improvement. However, I also tried 0.3weight percent cadmium and I did find some improvement with cadmium,although some of the cadmium appeared to be volatilizing from thecatalyst. Then I tried a lower lever weight percent cadmium which alsogave some improvement. Then I decided to go back and again try the zincaddition which I had earlier given up on. This time zinc did not detractfrom the catalyst but instead I found that the added zinc, which was inthe range of 0.01 to 0.3 weight percent, markedly improved the foulingstability of the catalyst.

One of the advantages of the Group IIB additive that I found is that itallows comparable catalyst performance at lower metal levels. Thus, aplatinum-rhenium reforming catalyst has been found to perform as well orbetter at 0.2 weight percent platinum, 0.2 weight percent rhenium, 0.06weight percent zinc compared to a similar catalyst in the same catalyticreforming service at 0.3 weight percent platinum, 0.3 weight percentrhenium but with no zinc. A particularly preferred embodiment of thepresent invention comprises catalytic reforming using a catalystcomprising less than 0.3 weight percent platinum and less than 0.3weight percent of said second component (especially rhenium orgermanium) but with an added Group IIB component (especially zinc).

DESCRIPTION OF THE DRAWINGS

The present invention may be better understood and will be furtherexplained hereinafter by reference to the Figures.

FIG. 1 illustrates that the fouling rate of a catalyst comprising 0.3weight percent platinum and 0.06 weight percent zinc is considerablylower than the fouling rate of a catalyst comprising 0.3 weight percentplatinum without zinc.

FIG. 2 illustrates that the fouling rate of a catalyst comprising 0.3weight percent platinum, 0.3 weight percent rhenium and 0.06 weightpercent zinc is considerably less than the fouling rate of a catalystcomprising 0.3 weight percent platinum and 0.3 weight percent rheniumwithout zinc.

FIG. 3 illustrates that the yield stability of a catalyst comprising 0.3weight percent platinum, 0.3 weight percent rhenium and 0.06 weightpercent zinc is as good or better than the yield stability of a catalystcomprising 0.3 weight percent platinum and 0.3 weight percent rheniumwithout zinc.

FIG. 4 illustrates that the fouling rate of a conventional catalystcomprising platinum and chlorine on alumina support is improved whenmercury is included with said catalyst.

FIG. 5 illustrates that the yield stability of a conventional catalystcomprising platinum and chlorine on alumina support is not adverselyaffected by including mercury therewith.

FIG. 6 illustrates that the fouling rate of a conventional catalystcomprising 0.3 weight percent platinum on an alumina support issignificantly improved by including cadmium with said catalyst.

FIG. 7 illustrates that the yield stability as a function of time ortemperature of a conventional catalyst comprising 0.3 weight percentplatinum on alumina support is significantly improved by includingcadmium with said catalyst.

FIG. 8 illustrates that the fouling rate of a platinumgermanium catalyston an alumina support is significantly improved by including zinc withsaid catalyst.

FIG. 9 illustrates that the yield stability as a function of time ortemperature of a platinum-germanium catalyst on an alumina support issignificantly improved by including zinc with said catalyst.

DESCRIPTION OF THE INVENTION

The porous solid carrier or support which is employed in the preparationof the catalyst of the present invention can be any of a large number ofmaterials upon which catalytically active amounts of a platinum groupcomponent, a Group IIB component, and a halogen component can beincluded. Preferably, the porous solid carrier is an inorganic oxide. Ahigh surface area inorganic oxide carrier is particularly preferred,e.g., an inorganic oxide having a surface area of greater than 50 m²/gm. Generally, the porous inorganic oxides which are useful as catalystsupports for the present invention have surface areas from about 50 to750 m² /gm.

For reforming processes, it is generally preferred that that catalysthas low cracking activity, that is, has limited acidity. It is preferredfor reforming processes to use inorganic oxide carriers such as magnesiaand alumina. Alumina is particularly preferred for purposes of thisinvention. Any of the forms of alumina suitable as a support forreforming catalysts can be used, e.g., gamma alumina, eta alumina, etc.Gamma alumina is particularly preferred. Furthermore, alumina can beprepared by a variety of methods satisfactory for the purposes of thisinvention. Thus, the alumina may be prepared by adding a suitablealkaline agent such as ammonium hydroxide to a salt of aluminum, such asaluminum chloride, aluminum nitrate, etc., in an amount to form aluminumhydroxide which on drying and calcining is converted to alumina. Aluminamay also be prepared by the reaction of sodium aluminate with a suitablereagent to cause precipitation thereof with the resulting formation ofaluminum hydroxide gel. Also, alumina may be prepared by the reaction ofmetallic aluminum with hydrochloric acid, acetic acid, etc., in order toform a hydrosol which can be gelled with a suitable precipitating agent,such as ammonium hydroxide, followed by drying and calcination.

Natural or synthetically produced inorganic oxides or combinationsthereof can also be used. Typical acidic inorganic oxide supports whichcan be used are the naturally occurring aluminum silicates, particularlywhen acid treated to increase the activity, and the syntheticallyproduced cracking supports, such as silica-alumina, silica-zirconia,silica-alumina-zirconia, silica-magnesia, silica-alumina-magnesia, andcrystalline zeolitic aluminosilicates.

For hydrocracking processes it is generally preferred that the carriercomprises a siliceous oxide. Generally, preferred hydrocrackingcatalysts contain silica-alumina, particularly silica-alumina having asilica content in the range of 30 to 99 weight percent.

The catalyst of the present invention in the broadest sense comprises aplatinum group component, a Group IIB component, and a halogen inassociation with a porous solid carrier, particularly a porous inorganicoxide carrier. The platinum group component should be present in anamount of from 0.01 to 5 weight percent, preferably from 0.01 to 3weight percent, based on the finished catalyst. The platinum groupcomponent embraces all the members of Group VIII of the Periodic Tablehaving an atomic weight greater than 100, i.e., ruthenium, rhodium,palladium, osmium, iridium, and platinum, as well as compounds andmixtures of any of these. Thus, the platinum group components are theGroup VIII noble metals or compounds thereof.

Platinum and platinum plus iridium are the preferred platinum groupcomponents because of their better performance in reforming and otherhydroconversion reactions. When the platinum is used as the platinumgroup component with or without iridium, particularly in reformingprocesses, the preferred amount is from 0.01 to 3, more preferably 0.1to 2 weight percent, and still more preferably 0.1 to 0.9 weightpercent. As previously stated, one of the advantages of the presentinvention is that low platinum levels can be used because the addedGroup IIB component has been found to "make-up" for the withdrawal ofsubstantial amounts of the very expensive platinum. Thus, especiallypreferred platinum levels are below 0.3 weight percent, e.g., 0.2 weightpercent or lower.

When platinum plus iridium is used, the preferred concentration ofiridium is 0.001 to 1 weight percent, more preferably 0.01 to 0.3 weightpercent.

Regardless of the form in which the platinum group component exists onthe carrier, whether as metal or compound, e.g., as an oxide, halide,sulfide, or the like, the weight percent is calculated as the metal.Reference to "platinum", "iridium", "platinum group component", etc., ismeant to refer to both the metal and the compound form.

The Group IIB component is present on the catalyst in an amount of from0.01 to 5 weight percent and preferably from 0.01 to 3 weight percentand more preferably from 0.1 to 1.5 weight percent, based on thefinished catalyst. When the platinum group component is platinum plusiridium and/or when a second catalyst component, preferably a rhenium,tin, germanium, and/or lead component is present, the still morepreferred amount of the Group IIB component is from 0.1 to 1.0 weightpercent. Furthermore, as previously stated, it is especially preferredto use Group IIB metal levels below 0.5 weight percent, and that levelsunder 0.3 weight percent have been found particularly advantageous,e.g., levels in the range 0.01 to 0.2 weight percent. The Group IIBcomponent can exist as an oxide, sulfide, or the like. Reference to"Group IIB" is meant to refer to both the metal and the compound form ofthe Group IIB metals, zinc, cadmium, and mercury. Regardless of the formin which the Group IIB component exists on the carrier, whether as themetal or in compound form, the weight percent is calculated as themetal.

When a rhenium component, a tin component, a germanium component, and/ora lead component is present, it is usually in an amount from 0.01 to 3weight percent of the final composition and preferably from 0.01 to 1.0weight percent. The weight percent is calculated as the metal.

The platinum group component, Group IIB component, and second catalystcomponent, preferably a rhenium, tin, germanium and/or lead component,when present, can be intimately associated with the porous solid carrierby suitable techniques such as ion exchange, precipitation,coprecipitation, etc. Preferably, however, the components are associatedwith the porous solid carrier by impregnation. Furthermore, one of thecomponents can be associated with the carrier by one procedure, e.g.,ion exchange, and the other component associated with the carrier byanother procedure, e.g., impregnation. As indicated, however, thecomponents are preferably associated with the carrier by impregnation.The catalyst can be prepared by either coimpregnation of the platinumgroup component, Group IIB component, and second catalyst component,when present, or by sequential impregnation.

The platinum group component is preferably associated with the poroussolid carrier by impregnation of water soluble compounds of the platinumgroup metals. For example, platinum may be added to the support byimpregnation from an aqueous solution of chloroplatinic acid. Otherwater soluble compounds of platinum which may be incorporated as part ofthe impregnation solution are, for example, ammonium chloroplatinates,platinum chloride, polyammine platinum salts, etc. Iridium compoundssuitable for including with the carrier include, among others,chloroiridic acid, iridium tribromide, ammonium chloroiridate, iridiumtrichloride, and ammonium bromoiridate. Compounds of the other platinumgroup components may be used as, for example, palladium chloride,rhodium chloride, etc. Impregnation solutions using organic solvents mayalso be used.

The Group IIB component is preferably associated with the porous solidcarrier suitably by adsorption or impregnation. Impregnation can beaccomplished using an aqueous or nonaqueous solution of a suitablecompound.

Suitable Group IIB compounds which can be used for impregnation are thechlorides, nitrates, sulfates, acetates and ammine complexes. Also,useful Group IIB compounds include the organic zinc, cadmium, andmercury compounds.

When the Group IIB compound comprises zinc and when a second catalystcomponent is included with the catalyst, and especially when said secondcomponent is a rhenium component, it is preferred that the zinccomponent be included (e.g., by impregnation) with the catalyst prior tothe inclusion of the second catalyst component, e.g., rhenium,therewith.

Rhenium compounds suitable for including onto the carrier include, amongothers, perrhenic acid and ammonium perrhenates in aqueous solution.

Tin compounds suitable for including onto the carrier include, amongothers, the chlorides, nitrates, sulfates, acetates, and aminecomplexes. Other useful tin compounds include the organic tin compounds,such as the tetra-alkyl compound (tetrabutyl, -phenyl, -ethyl, -propyl,-octyl, -decyl, tin and the like), and the tetra-alkoxide compounds (tintetraethoxides, etc.). The tin can be in the stannous or stannicoxidation state.

Germanium compounds suitable for including onto the carrier include,among others, the chlorides, e.g., tetrachlorides and the other halides,nitrates, sulfates, acetates, and amine complexes. Also useful germaniumcompounds include the organic germanium compounds, such as thetetra-alkoxide compounds (germanium tetraethoxides, etc.).

Lead compounds suitable for including onto the carrier include, amongothers, lead chloride, lead nitrate, organic lead compounds such astetraethyl lead and the like.

It is advantageous to promote the catalyst for hydrocarbonhydroconversion reactions by the addition of combined halogens(halides), particularly fluorine or chlorine. Bromine may also be used.The catalyst promoted with halogen usually contains from 0.1 to 10weight percent, preferably 0.1 to 3 weight percent, total halogencontent. When the halogen is chlorine, it even more preferably contains0.5 to 2.0 weight percent and still more preferably 0.8 to 1.6 weightpercent, total chlorine content. The preferred amounts are particularlydesirable in reforming. The halogens may be incorporated onto thecatalyst at any suitable stage of catalyst manufacture, e.g., prior toor following incorporation of the platinum group component and Group IIBcomponent. Also, halogen may be incorporated with the catalyst by addingvolatile, usually organic, halogens during a hydroconversion processalong with the feed. Generally, the halogens can be combined with thecatalyst by contacting suitable compounds such as hydrogen fluoride,ammonium fluoride, hydrogen chloride and ammonium chloride, either inthe gaseous form or in the water soluble form with the catalyst.Preferably the fluorine or chlorine is incorporated with the catalystfrom an aqueous solution containing the halogen. Often halogen isincorporated with the catalyst by impregnating with a solution of ahalogen compound of a platinum group metal, Group IIB component and/orsecond catalyst component. Thus, for example, impregnation withchloroplatinic acid normally results in chlorine addition to thecatalyst.

Following incorporation of the porous solid carrier with the platinumgroup component, the Group IIB component, the second catalyst component,if present, and the halogen, the resulting composite is usually treatedby heating at a temperature of, for example, no greater than 500° F. andpreferably at 200° to 400° F. Thereafter the composite can be calcinedat an elevated temperatures, as, for example, up to 1300° F., ifdesired. In the case of sequential deposition of the metal componentsonto the porous solid carrier, it may be desirable to dry and calcinethe catalyst after the introduction of one of the metal components andprior to introduction of the other.

Following calcination, the catalyst containing a platinum groupcomponent and a Group IIB component, and a second catalyst component, ifpresent, is preferably heated at an elevated temperature in a hydrogencontaining atmosphere, preferably dry hydrogen to produce the catalystin reduced form. It is particularly preferred that this treatment withhydrogen be accomplished at a range of 600° to 1200° F. and preferablyfrom 600° to 1000° F. The heating in the presence of hydrogen preferablycontinues until the partial pressure of hydrogen substantiallystabilizes. This will usually take 5 minutes or longer. The treatment inthe presence of hydrogen should be accomplished in a hydrocarbon-freeenvironment. Thus, any hydrocarbon on the catalyst should be removedprior to contact with the hydrogen. The environment should also besubstantially free of carbon oxides. By "reduced form" it is not meantto imply that the entire catalyst or even all of the platinum groupcomponent and Group IIB component and second catalyst component, ifpresent, are reduced to a zero valence state, although the greatmajority of the platinum group component is believed to be reduced tothe metal (zero valence). The reduction of the catalytic composition asdescribed above to form a reduced catalytic composition enhances theusefulness of the catalytic composition in, for example, reformingprocesses. Overheating and overly long heating during reduction shouldbe avoided since this may lead to the loss of a substantial amount ofthe Group IIB component, especially if the Group IIB component ismercury or cadmium.

The novel catalytic composition of the present invention finds utilityfor various hydrocarbon hydroconversion reactions including hydrofining,hydrogenation, reforming, alkylation, dehydrocyclization, isomerization,and hydrocracking. The catalyst composition of the present invention ismost advantageously used for reforming. The hydrocarbon feeds employedand the reaction conditions used will depend upon the particularhydrocarbon hydroconversion process involved and are generally wellknown in the petroleum art. The conditions of temperature, pressure,hydrogen flow rate, and liquid hourly space velocity in the reactionzone can be correlated and adjusted depending on the particularfeedstock utilized, the particular hydrocarbon hydroconversion process,and the products desired. For example, hydrocracking operations aregenerally accomplished at a temperature of from about 450° to 900° F.and a pressure between about 500 to 10,000 psig. Preferably pressuresbetween 1200 to 1600 psig are used. The hydrogen flow rate into thereactor is maintained between 1000 to 20,000 SCF/bbl of feed andpreferably in the range 2000 to 10,000 SCF/bbl. The liquid hourly spacevelocity (LHSV) will generally be in the range of from 0.1 to 10 andpreferably from 0.3 to 5.

As indicated above, the catalyst of the present invention is preferablyemployed in reforming. The feedstock desirably used for reforming is alight hydrocarbon oil, e.g., a naphtha fraction. Generally, the naphthawill boil in the range falling within the limits of from 70° to 550° F.and preferably from 150° to 450° F. The feedstock can be, for example,either a straight-run naphtha or a thermally-cracked orcatalytically-cracked naphtha or blends thereof. The feedstock canpreferably be low in sulfur, i.e., preferably contain less than 10 ppmsulfur and more preferably less than 5 ppm sulfur. In the case of afeedstock which is not already low in sulfur, acceptable levels can bereached by hydrogenating the feedstock in a presaturation zone where thenaphtha is contacted with a hydrogenation catalyst which is resistant tosulfur poisoning. A suitable catalyst for this hydrodesulfurizationprocess is, for example, an alumina-containing support with a minorproportion of molybdenum oxide and cobalt oxide. Hydrodesulfurization isordinarily conducted at a temperature of from 700° to 850° F., apressure of from 200 to 2000 psig, and a liquid hourly space velocity offrom 1 to 5. The sulfur contained in the naphtha is converted tohydrogen sulfide which can be removed prior to reforming by suitableconventional processes.

The feedstock can preferably be low in moisture, i.e., preferablycontain less than 50 ppm water (by weight) and more preferably less than15 ppm moisture. This limits the amount of moisture that contacts thecatalyst and thereby serves to keep the activity of the catalyst highfor longer periods of time.

Reforming conditions will depend in large measure on the feed used,whether highly aromatic, paraffinic or naphthenic, and upon the desiredoctane rating of the product. The temperature in the reforming processwill generally be in the range of about 600° to 1100° F. and preferablyabout 700° to 1050° F. The pressure in the reforming reaction zone canbe atmospheric or superatmospheric. The pressure will generally liewithin the range from 25 to 1000 psig, preferably from about 50 to 750psig, and more preferably from about 50 to 300 psig. The temperature andpressure can be correlated with the liquid hourly space velocity (LHSV)to favor any particularly desirable reforming reaction as, for example,dehydrocyclization, or isomerization. Generally, the liquid hourly spacevelocity will be from 0.1 to 10, and preferably from 1 to 5. The use ofthe catalysts of the present invention (especially Pt-Re and Pt-Gespecies) in catalytic reforming allows the use of relatively higherspace velocities and/or lower pressures and/or lower H₂ to hydrocarbonreactor feed ratios for catalytic reforming than is allowable withsimilar catalysts containing no Group IIB component and used to achievea given reformer performance (given product octane, given fouling rate,etc.).

Reforming of a naphtha is accomplished by contacting the naphtha atreforming conditions and in the presence of hydrogen with the desiredcatalyst. Reforming generally results in the production of hydrogen. Thehydrogen produced during the reforming process is generally recoveredfrom the reaction products and preferably at least part of said hydrogenis recycled to the reaction zone. Preferably, the recycle hydrogen issubstantially dried, as by being contacted with an adsorbent materialsuch as molecular sieve, prior to being recycled to the reaction zone.Thus, excess or makeup hydrogen need not necessarily be added to thereforming process, although it is sometimes preferred to introduceexcess hydrogen at some stage of the operation, for example, duringstartup. Hydrogen, either as recycle or makeup hydrogen, can be added tothe feed prior to contact with the catalyst or can be contactedsimultaneously with the introduction of feed to the reaction zone.Generally, during startup of the process, hydrogen is recirculated overthe catalyst prior to contact of the feed with the catalyst. Hydrogen ispreferably introduced into the reforming reaction zone at a rate of fromabout 0.5 to 20 moles of hydrogen per mole of feed. The hydrogen can bein admixture with light gaseous hydrocarbons.

It may be desirable in some instances, especially if the catalystcontains a rhenium component, to presulfide the catalyst prior to use incatalytic hydroconversion reactions, for example, reforming. Thepresulfiding can be done in situ or ex situ by passing asulfur-containing gas, e.g., H₂ S, and hydrogen through the catalystbed. A temperature of from 25 to 1100° F. or more can be used for thepresulfiding. Other presulfiding treatments are known in the prior art.It may also be desirable on startup of the reforming process to use asmall amount of sulfur, e.g., H₂ S or dimethylsulfide. The sulfurcompound is added to the reforming zone in the presence of the flowinghydrogen. The sulfur can be introduced into the reaction zone in anyconvenient manner and at any convenient location. It can be contained inthe liquid hydrocarbon feed, the hydrogen-rich gas, the recycle gasstream or any combination.

After a period of operation when the catalyst becomes deactivated by thepresence of carbonaceous deposits, the catalyst can be regenerated, forexample, by passing an oxygen-containing gas having no more than about 2percent oxygen, into contact with the catalyst at an elevatedtemperature in order to burn carbonaceous deposits from the catalyst.The method of regenerating the catalyst will depend on whether there isa fixed bed, moving bed, or fluidized bed operation.

It is usually desirable to activate the catalyst after it has beenregenerated by reacting it with an activating gas at a temperature of700° F. -1200° F. for at least 0.5 hour and preferably from 0.5 hour to24 hours, said activating gas including oxygen, preferably at leastabout 0.5 percent oxygen. More preferably, said activating gas alsoincludes at least about 0.05 psia water. The activating technique isespecially useful when the catalyst contains a tin component. When a tincomponent is present it is also preferable to activate the freshcatalyst. It is generally preferred to include a halogenating componentwith the activating gas when activating a deactivated and regeneratedcatalyst. The reason for this is that the deactivated and regeneratedcatalyst may have lost some halogen content during its use in ahydrocarbon hydroconversion process. The catalyst may be analyzed forhalide content to determine whether a halogenating component should beincluded with the activating gas.

After regeneration, or regeneration and activation if the catalyst isactivated, the catalyst is preferably heated at an elevated temperaturein a hydrogen containing atmosphere to reduce it. Preferably, theheating is performed in the presence of a substantiallyhydrocarbon-free, hydrogen containing gas that is preferablysubstantially dry at a temperature from 600° F. to 1200° F., and morepreferably from 600° F. to 1000° F. The substantially hydrocarbon-freehydrogen-containing gas is preferably also free of carbon oxides andwater.

EXAMPLES

The process of the present invention will be more readily understood byreference to the following Examples.

EXAMPLE 1 Platinum-Zinc Catalyst and Process

A catalyst, Catalyst A, comprising platinum and zinc in association withalumina was prepared by adsorbing ZnCl₂ and HCl on PHF-4 catalyst. PHF-4catalyst is a commercially available catalyst made by American CyanamidCompany. The PHF-4 catalyst contained 0.3 weight percent platinum and0.6 weight percent chlorine. The impregnated catalyst was driedovernight at about 300° F. The catalyst was calcined in flowing air forabout 1 hour at 900° F. and then reduced in 1 to 2 atmospheres ofhydrogen for 1 hour at 920° F. The resulting catalyst contained 0.3weight percent platinum, 0.06 weight percent zinc and 1.0 weight percentchlorine.

Another catalyst, Catalyst B, comprising platinum and chlorine inassociation with alumina was prepared as follows. A PHF-4 catalyst wasimpregnated with hydrochloric acid. The impregnated catalyst was thendried, reduced and calcined substantially as above. The resultingcatalyst contained 0.3 weight percent platinum and 0.9 weight percentchlorine.

Catalysts A and B were individually tested for reforming the naphthafeed having a boiling range of 151° F. to 428° F. comprising 23.4 volumepercent aromatics, 36.5 volume percent parafffins and 40.1 volumepercent naphthenes. The feed was essentially sulfur-free andnitrogen-free. Reforming conditions included a pressure of 160 psig, aliquid hourly space velocity of 4.0 and a hydrogen-to-hydrocarbon moleratio of 3.0. Once-through hydrogen was used in the reforming test. Thetemperature during the reforming test was adjusted to maintainconversion to 99 F-1 clear octane product.

The reforming processes were conducted under conditions chosen tosimulate an accelerated life test for the catalysts. These conditionswere not necessarily maintained at levels used in a commercial reformingprocess, but, in general, were much more severe to test in a relativelyfew hours how well the catalyst would perform.

The increase in temperature necessary to maintain conversion 99 F-1clear octane product was measured for Catalysts A and B to give anindication of the activity and temperature stability of each catalyst.The results are shown in the graphs in FIG. 1. FIG. 1 illustrates thatCatalyst A, which contains 0.06 weight percent zinc promoter, exhibits alower fouling rate under identical reforming conditions than doesCatalyst B, which does not contain any zinc.

The change in yield of C₅ + gasoline product over the period of the runwas also measured for each catalyst to give an indication of the yieldstability of each catalyst. The C₅ + gasoline product yield, saidproduct having an octane rating of 99 F-1 clear, was about the same forboth catalysts.

EXAMPLE 2 Platinum-Rhenium-Zinc Catalysts and Processes

A catalyst, Catalyst C, comprising platinum, rhenium and zinc inassociation with alumina was prepared by adsorbing ZnCl₂ and HCl ontoPHF-4 catalyst and then impregnating the catalyst with perrhenic acid.The catalyst was then dried overnight at about 300° F. The catalyst wascalcined in flowing air for about 1 hour at 900° F. and then reduced in1 to 2 atmospheres of hydrogen for 1 hour at 920° F. The resultingcatalyst contained 0.3 weight percent platinum, 0.3 weight percentrhenium, 0.06 weight percent zinc and 1.1 weight percent chlorine.

Another catalyst, Catalyst D, comprising platinum, rhenium and chlorinein association with alumina was prepared as follows. A PHF-4 catalystwas impregnated with perrhenic acid and then hydrochloric acid. Thiscatalyst was then dried, reduced and calcined substantially as above.The resulting catalyst contained 0.3 weight percent platinum, 0.3 weightpercent rhenium and 1.0 weight percent chlorine.

Catalysts C and D were individually tested for reforming the naphtha ofExample 1 under the conditions of Example 1.

The increase in temperature necessary to maintain conversion to 99 F-1clear octane product was measured for Catalysts C and D to give anindication of the activity and temperature stability of each catalyst.The results are shown in the graph in FIG. 2.

FIG. 2 illustrates that Catalyst C, which contains 0.06 weight percentof a zinc promoter, exhibits a lower fouling rate under identicalreforming conditions than does Catalyst D which does not contain a zincpromoter. The change in yield of C₅ + gasoline product over the periodof the run was also measured for each catalyst to give an indication ofthe yield stability of each catalyst. The C₅ + gasoline product yield,said product having an octane rating of 99 F-1 clear, is shown in FIG.3. FIG. 3 illustrates that Catalyst C, which contains 0.06 weightpercent of a zinc promoter, exhibits at least as low of a yield declineas does Catalyst D which does not contain a zinc promoter.

The data presented in Examples 1 and 2 demonstrate that zinc iseffective in improving the fouling rate of a platinum catalyst and aplatinum-rhenium catalyst to an unexpectedly great extent.

EXAMPLE 3 Platinum-Mercury Catalyst and Process

Two catalysts were prepared: A comparison catalyst of the prior art(Catalyst P) having 0.3 weight percent platinum and 1.0 weight percentchlorine associated with an alumina support and a catalyst in accordancewith the invention (Catalyst E) comprising 0.3 weight percent platinum,0.3 weight percent mercury and 1.0 weight percent chlorine associatedwith an alumina support. Both Catalyst P and Catalyst E were preparedfrom PHF-4 catalyst. Catalyst E was prepared by impregnating PHF-4catalyst with mercuric chloride. Each of the catalysts was dried byheating the catalyst overnight at 300° F. Each of the catalysts wascalcined at 900° F. for 1 hour. A portion of Catalyst E was analyzedafter calcining and was found to contain 0.053 weight percent mercury,i.e., the mercury content was reduced by the calcining, but asignificant amount of mercury remained on the catalyst. Each of thecatalysts was reduced, after the calcining, in 1 to 2 atmosphereshydrogen at a temperature of about 920° F. for about 1 hour. Catalyst Pwas sulfided at the end of being reduced in a hydrogen atmosphere.Catalyst E was sulfided after 11/2 hours on-stream in the reformingprocess described below.

Catalysts P and E were tested for reforming of a naphtha feed having aboiling range of 151° F. too 428° F. comprising 23.4 volume percentaromatics, 36.5 volume percent paraffins, and 40.1 volume percentnaphthenes. The feed was essentially sulfur-free and nitrogen-free.Reforming conditions included a pressure of 160 psig, a liquid hourlyspace velocity of 4.0 and a hydrogen-to-hydrocarbon mole ratio of 3.0.Once-through hydrogen was used in the reforming test. The temperatureduring the reforming test was adjusted to maintain conversion to 99 F-1clear octane product.

The reforming processes were conducted under conditions chosen tosimulate an accelerated life test for the catalysts. These conditionswere not necessarily maintained at levels used in a commercial reformingprocess, but, in general, were much more severe to test in a relativelyfew hours how well the catalyst would perform. The increase intemperature necessary to maintain conversion to 99 F-1 clear octaneproduct was measured for each catalyst to give an indication of theactivity and temperature stability of each catalyst. The results areshown in the graphs in FIG. 4.

The change in yield of C₅ + gasoline product over the period of the runwas also measured for each catalyst to give an indication of the yieldstability of each catalyst. The C₅ + gasoline product yield, saidproduct having an octane rating of 99 F-1 clear is shown in FIG. 5.

Catalyst E in the reforming test exhibited a lower fouling rate (1.6°F./hour) than did Catalyst P (1.8° F./hour). As may be seen from FIG. 4,it was necessary to increase the temperature more rapidly for theprocess using the platinum catalyst without mercury in order to maintaina 99 F-1 clear octane product. The yield of C₅ + liquid product havingthe desired octane rating was substantially the same as a function oftime on-stream with Catalyst P as with Catalyst E. It was necessary topre-sulfide both Catalyst P and Catalyst E to prevent excessivehydrocracking on startup.

EXAMPLE 4 Platinum-Cadmium Catalyst and Process

A catalyst, Catalyst F, comprising platinum, cadmium and chlorine, wasprepared by the same method as was Catalyst F except that cadmiumchloride was used in place of mercury chloride. Catalyst F was dried ata temperature of 300° F. overnight. Catalyst F was then calcined inflowing air for about 1 hour at 900° F. and was then reduced in 1 to 2atmospheres of hydrogen for 1 hour at 920° F. The resulting catalystcontained 0.3 weight percent platinum, 0.3 weight percent cadmium, and1.0 weight percent chlorine. Catalyst F was not sulfided.

Catalyst F was tested for reforming the naphtha feed of Example 1 underthe same reforming conditions of Example 1. A sample of Catalyst F wasanalyzed for cadmium content at the end of the reforming run. Thisportion of Catalyst F was found to contain approximately 0.06 weightpercent cadmium.

The increase in temperature necessary to maintain conversion to 99 F-1clear octane product was measured for Catalyst F to give an indicationof the activity and temperature stability of this catalyst. The resultsare shown in the graph in FIG. 6. The results using Catalyst P arerepeated in FIG. 6 for comparison purposes. The change in yield of C₅ +gasoline product over the period of the run was measured for Catalyst Fto give an indication of the yield stability of this catalyst. The C₅ +gasoline product yield, said product having an octane rating of 99 F-1clear, is shown in FIG. 7 as is the corresponding data for Catalyst P.

Catalyst F is clearly superior to Catalyst P. FIG. 6 illustrates thatthe fouling rate of Catalyst F is less than half the fouling rate ofCatalyst P. FIG. 7 illustrates that the yield of C₅ + liquid producthaving the desired octane rating decreased significantly for the processusing Catalyst P whereas Catalyst F performed remarkably well during thereforming test in that the yield of C₅ + liquid product remained higheven after 60 hours on-stream. Further, Catalyst F was not sulfidedprior to use in the reforming test. As can be seen from examination ofthe initial portion of the graph for Catalyst F in FIG. 7 excessivehydrocracking did not occur with Catalyst F. Catalyst P, on the otherhand, was a sulfided catalyst since, in the absence of sulfur, CatalystP would have given excessive hydrocracking in the initial period ofreforming.

EXAMPLE 5 Retention of Cadmium During Reforming

Three catalysts comprising platinum and cadmium associated with aluminawere prepared and were tested for reforming the naphtha of Example 1under the conditions of Example 1. The presence of cadmium in each ofthe catalysts led to a lower fouling rate than was found with similarcontrol catalysts which did not contain cadmium. The cadmium content ofeach of the three catalysts was determined both before the start of thereforming run and at the end of the reforming run. The following tablesets out the cadmium contents.

    ______________________________________                                        Cadmium Content    Cadmium Content                                            Before Reforming, Wt. %                                                                          After Reforming, Wt. %                                     ______________________________________                                        .085               .064                                                       .037               .051                                                       .033               .025                                                       ______________________________________                                    

The data in the table above illustrates that within experimental errorthe cadmium contents of the catalysts comprising platinum and cadmiumassociated with alumina did not decrease significantly during reforming.

EXAMPLE 6 Platinum-Germanium-Zinc Catalysts and Processes

A catalyst, Catalyst G, comprising platinum, germanium, and zinc inassociation with alumina, was prepared as follows: The alumina used wasa 1/16-inch extrudate of high purity gamma alumina with a surface areaof approximately 190 square meters per gram. It was obtained from theAmerican Cyanamid Company and was designated AEROEXTRUDATE 9999. Thiscatalyst base was soaked in an aqueous solution of zinc chloridecontaining excess free HCl. The zinc and some of the chloride werechemisorbed on the alumina. The alumina was then dried and calcined forone hour in air at 900° F.

Platinum and germanium were coimpregnated on the zinccontaining alumina.Germanium dioxide was first reduced with hydrogen and then dissolved inchlorine water. Chloroplatinic solution so obtained was used toimpregnate the zinc-containing alumina described above. Afterimpregnation, the catalyst was dried and calcined for two hours at 950°F. in air. The final catalyst contained 0.3 percent platinum, 0.4percent germanium, 0.09 percent zinc and 0.8 percent chlorine.

A comparison catalyst, Catalyst H, comprising platinum and germanium inassociation with aluminum but without the presence of zinc, was alsoprepared. The method of preparation was identical to that described forCatalyst G above except that the zinc impregnating step was omitted.Catalyst H contained 0.3 percent platinum, 0.4 percent germanium, and0.6 percent chlorine.

Catalysts G, H, and D (prepared in Example 2) were compared in acatalytic reforming test. The naphtha feed used was the same onedescribed in Example 1. The reforming conditions included a pressure of100 psig, a liquid hourly space velocity of 3.0, andhydrogen-hydrocarbon mole ratio of 3.0 Once-through hydrogen was used.The temperature during the reforming test was adjusted to maintain theF-1 clear octane number product at 100. These conditions were chosen togive a rapid comparison of the three catalysts and are much more severethan those customarily used in a commercial reforming process.

The increase in temperature necessary to maintain conversion to 100 F-1clear octane number product was measured for Catalysts G, H and D togive an indication of the activity and temperature stability of each ofthese catalysts. The results are shown in the graphs in FIG. 8. Thetemperature initially required to obtain the desired octane numberproduct was approximately the same for the three catalysts. However, inorder to maintain this octane number, it was necessary to raise thetemperature with Catalysts D and H much more rapidly than with CatalystG. FIG. 8, therefore, demonstrates that the zinc in Catalyst Gsubstantially lowers the fouling rate in comparison with the twocatalysts which do not contain zinc.

In FIG. 9, the liquid volume percent yield of C₅ + product is plottedagainst the hours on-stream for the same three runs illustrated in FIG.8. The initial yield for Catalyst G is higher than for the other twocatalysts, and it declines more slowly as the run progresses. This againdemonstrates the beneficial effect of zinc in improving the stability ofa catalyst comprising platinum and germanium.

The data from the runs for these three catalysts are summarized in thefollowing table. Fouling rates are given in degrees Fahrenheit per hour,and the C₅ + yields tabulated are those measured in the early part ofthe runs before the decline in yield had set in. The superiority of thezinc-containing catalyst in both fouling rate and yield is clearlyapparent.

    ______________________________________                                                               Fouling  C.sub.5 + Yield,                              Catalyst    Catalyst   Rate,    Liquid                                        Designation Components °F/Hr                                                                           Vol. %                                        ______________________________________                                        G           Pt, Ge, Zn 2.65     86.8                                          H           Pt, Ge     3.50     86.4                                          D           Pt, Re     4.00     85.4                                          ______________________________________                                    

Catalysts G and H were also compared for their ability to aromatizenormal paraffins. In this case, the conditions were also 100 psig, 3.0liquid hourly space velocity, and 3.0 mole ratio of hydrogen tohydrocarbon. The feed was normal decane and the runs were conducted at atemperature which gave 82 weight percent of aromatics in the C₅ +product. The starting temperatures for Catalysts G and H wereessentially identical, 932° F. and 933° F., respectively. The foulingrates in this case were also nearly the same; 1.00° F. per hour forCatalyst G and 0.95° F. per hour for Catalyst H. There was anappreciable difference, however, in the liquid volume percent yield ofC₅ + product. Catalyst G produced 75.8 percent while Catalyst H produced75.0 percent. The increase of 0.8 percent in C₅ + yield indicates thatzinc has a beneficial effectt on improving selectivity for thearomatization of paraffins of a catalyst containing platinum andgermanium.

The foregoing disclosure of this invention is not to be considered aslimiting since many variations can be made by those skilled in the artwithout departing from the scope or spirit of the appended claims.

That which is claimed is:
 1. A process for the reforming of a naphthafeedstock which comprises contacting the feedstock at reformingconditions and in the presence of hydrogen with a catalyst comprising0.01 to 3 weight percent of a platinum component, 0.01 to 5 weightpercent of a Group IIB component, 0.01 to 3 weight percent of a catalystcomponent selected from the group consisting of a rhenium component, anda germanium component, and 0.1 to 3 weight percent of a halogen inassociation with a porous solid carrier.
 2. A process as in claim 1,wherein the catalyst comprises less than 1.0 weight percent zinc.
 3. Aprocess as in claim 1, wherein the catalyst comprises less than 0.3weight percent zinc.
 4. A process as in claim 1, wherein the catalystcomprises platinum, rhenium and 0.01 to 5.0 weight percent zinc.
 5. Aprocess as in claim 4, wherein the zinc content is below 1.0 weightpercent.
 6. A process as in claim 4, wherein the zinc content is below0.3 weight percent.
 7. A process as in claim 4, wherein the platinumcontent is below 0.3 weight percent and the rhenium content below 0.3weight percent.
 8. A process as in claim 1, wherein the catalystcomprises platinum, germanium and 0.01 to 5.0 weight percent zinc.
 9. Aprocess as in claim 8, wherein the zinc content is below 1.0 weightpercent.
 10. A process as in claim 8, wherein the zinc content is below0.3 weight percent.
 11. A process as in claim 8, wherein the platinumcontent is below 0.3 weight percent and the germanium content is below0.3 weight percent.